package acm;

import java.util.Scanner;

public class 递归求二项式系数值 {
    public static void main(String[] args){
        Scanner in = new Scanner(System.in);
        int k = in .nextInt();
        int n = in .nextInt();
        int result = 0;
        int x=0,y=0,cs=1,bcs=1;
        if (k==1||k==n){
            result = 1;
        }
        else if (n>k&n>0){
            x=k;
            y=n;
            while (x>0){
                cs=cs*y;
                y--;
                x--;
            }
            for (int j=k;j>0;j--){
                bcs=bcs*j;
            }
            result = cs/bcs;

        }
        System.out.print(result);
    }
}
